To set the direction of a magnetic field formed on an arrangement surface where a ring substrate is to be arranged more completely parallel to the diameter direction of the ring substrate.
The magnetic circuit for generating a diameter-direction magnetic field includes a first ring-like permanent magnet unit and a second permanent magnet unit, a ring substrate to be processed is arranged in a space between the first and second permanent magnets and, when a plane including the ring substrate is set as an arrangement surface at the time of arranging the ring substrate, a magnetic field is generated in the diameter direction of the ring substrate on the arrangement surface. This magnetic circuit is arranged such that magnetic fields generated by the first and second permanent magnet units have magnetic field components in the diameter direction of the ring substrate, but substantially no magnetic field components in a peripheral direction.
Arihara Koichi
Matsushima Tetsuo
Hidefumi Kawamura